Oh ok, glad you did a search before you actually went through it.
It's not that bad, personally I can't really say much about it. But considering what little information we have about them it would be hard to wrap our minds around them being "materialized darkness" that alone sounds somewhat like the process in which a emblem heartless is made.
You might have to half ass it, but it's up to you; using some other facts wouldn't hurt either.